Time-of-flight-based distance measurement system and method

Abstract

This application provides a time of flight (TOF)-based distance measurement system with adjustable histograms, including: an emitter, configured to emit a pulsed beam; a collector, configured to collect a photon in the pulsed beam reflected by an object and form a photonic signal; and a processing circuit, connected to the emitter and the collector, and including a TDC circuit and a histogram circuit. The TDC circuit is configured to receive the photonic signal, calculate a time interval of the photonic signal, and convert the time interval into a time code. The histogram circuit counts photons on a corresponding internal time unit based on the time code, and collects statistics on photon counts in all time units after a plurality of measurements to draw a histogram. An address of the time unit can be dynamically adjusted to dynamically adjust a time resolution and/or a time range width of the histogram.

What is claimed is: 
     
         1 . A time of flight (TOF)-based distance measurement system, comprising:
 an emitter, configured to emit a pulsed beam;   a collector configured to collect a photon in the pulsed beam reflected by an object to generate a photonic signal; and   a processing circuit, connected to the emitter and the collector, and comprising a time-to-digital converter (TDC) circuit and a histogram circuit, wherein the TDC circuit is configured to receive the photonic signal, to calculate a time interval of the photonic signal and to convert the time interval into a time code, and the histogram circuit counts photons in a corresponding time unit based on the time code and collects statistics on photon counts in time units after a plurality of measurements to draw a histogram, wherein   an address of the time unit is dynamically adjusted to dynamically adjust a time resolution and/or a time range width of the histogram.   
     
     
         2 . The TOF-based distance measurement system according to  claim 1 , further comprising:
 determining a time corresponding to a pulse waveform in the histogram; and   determining a TOF of the pulsed beam according to the time corresponding to the pulse waveform.   
     
     
         3 . The TOF-based distance measurement system according to  claim 1 , wherein the collector comprises a single photon avalanche photodiode. 
     
     
         4 . The TOF-based distance measurement system according to  claim 1 , wherein the histogram circuit further comprises:
 an address decoder configured to receive the time code, and to convert the time code into address information;   a storage matrix comprising a plurality of time units configured to store a photon count value; and   a read/write circuit configured to perform an operation of adding one to a photon count of the time unit when the address information is consistent with the address of the time unit or is within an address range of the time unit.   
     
     
         5 . The TOF-based distance measurement system according to  claim 1 , wherein the system is dynamically adjusted to realize two modes: a coarse histogram mode and a fine histogram mode; and a time range width in the coarse histogram mode is greater than a time range width in the fine histogram mode. 
     
     
         6 . A time of flight (TOF)-based distance measurement method, comprising:
 emitting a pulsed beam;   collecting a photon in the pulsed beam reflected by an object to generate a photonic signal; and   receiving the photonic signal, calculating a time interval of the photonic signal, converting the time interval into a time code, counting photons in a corresponding time unit based on the time code, and collecting statistics on photon counts in time units after a plurality of measurements to draw a histogram, wherein   an address of the time unit is dynamically adjusted to dynamically adjust a time resolution and/or a time range width of the histogram.   
     
     
         7 . The TOF-based distance measurement method according to  claim 6 , further comprising:
 determining a time corresponding to a pulse waveform in the histogram; and   determining a TOF of the pulsed beam according to the time corresponding to the pulse waveform.   
     
     
         8 . The TOF-based distance measurement method according to  claim 6 , wherein the method is dynamically adjusted to realize two modes: a coarse histogram mode and a fine histogram mode; and a time range width in the coarse histogram mode is greater than a time range width in the fine histogram mode. 
     
     
         9 . The TOF-based distance measurement method according to  claim 7 , wherein the method is dynamically adjusted to realize two modes: a coarse histogram mode and a fine histogram mode; and a time range width in the coarse histogram mode is greater than a time range width in the fine histogram mode. 
     
     
         10 . The TOF-based distance measurement method according to  claim 8 , wherein a first histogram is drawn in the coarse histogram mode, and a second histogram is drawn in the fine histogram mode based on the first histogram. 
     
     
         11 . The TOF-based distance measurement method according to  claim 9 , wherein a first histogram is drawn in the coarse histogram mode, and a second histogram is drawn in the fine histogram mode based on the first histogram. 
     
     
         12 . The TOF-based distance measurement method according to  claim 10 , wherein the second histogram is used to determine a TOF of the pulsed beam. 
     
     
         13 . The TOF-based distance measurement method according to  claim 11 , wherein the second histogram is used to determine the TOF of the pulsed beam. 
     
     
         14 . The TOF-based distance measurement method according to  claim 6 , further comprising:
 converting the time code into address information; and   performing an operation of adding one to a photon count of the time unit when the address information is consistent with the address of the time unit or is within an address range of the time unit.